Drinking containers in modern times have been fabricated in both insulated and non-insulated constructions for use with beverages of various types. Since ancient times drinking cups for hot beverages such as tea have been designed with a handle external to the outer surface with two, or occasionally one, point(s) of attachment of sufficient dimension to support the weight of the container and maximum volume of liquid when lifted. Containers used for cold or room-temperature beverages, water and wine glasses for example, may have an insulating stem or no insulation at all. Insulated containers have the advantage of preserving the thermal properties of the beverage for longer than a conventional non-insulated mug or glass. They may have the further advantage of protecting the holder from discomfort, cold or even scalding, depending upon the specific design. Insulated containers have the disadvantages of manufacturing complexity, additional weight or size, or the constraint of having to incorporate non-conventional (e.g., plastics, not glass or ceramic) compounds, which may affect taste or “mouth feel,” and/or to affix separate or cumbersome external insulators.
Notwithstanding these disadvantages, the desirability of insulated containers is evident from the popularity of so-called travel mugs. For simplicity of reference, insulated drinking containers of all types will be hereinafter may be termed insulated containers or “mugs,” without limitation as to usage or design. Conventional glass or ceramic mugs of greater-than-usual wall thickness will have additional insulating properties due to dissipation of heat or preservation of cold by dint of the extra mass. These heavy mugs are generally more difficult and uncomfortable for the drinker to hold than an ordinary mug, particularly for persons with hand or wrist infirmities such as carpal-tunnel syndrome or arthritis. Thus, such persons and others may prefer the use of conventional, thinner-walled mugs for their comfort, with some additional risk to scalding or freezing. However, even conventional mugs with external handles have the property of placing the center of gravity considerably distal to the users' grasp, particularly when full of liquid, exerting an tortional pressure on the wrist and fingers.
Typically, there are three approaches to manufacturing an insulated mug. First is an inherently low thermally conducting material such as Styrofoam or similar, which is semi-porous, may lack rigidity and feels unlike household mugs. Second, an external insulator is affixed, permanently (e.g., foam handle or “grip-strip”) or removably (e.g., cardboard collar for paper coffee containers). Third, a double-walled container in which the inner cavity is either a vacuum or filled with air or insulating material.
In the prior art, conventional and externally insulated mug-bodies have circular cross-sections with their single or double-walls of constant and uniform thickness. The conventional handle for single wall mug is curvilinear and attached at either the top or at both ends to the mug body, while the insulated double-wall mug has either a handle or a grip strip for convenience. Insulated mugs are the generally of a double-wall type of construction with the space between the walls either vacuum sealed for optimum insulation or not vacuum sealed for nominal insulation. Placement of a handle farther from the outer perimeter of the mug provides further insulating properties, but at an increasingly distal center of gravity, giving the mug an unbalanced feeling, placing more strain on the holder's wrist.
A recent example of the affixation of insulation in the prior art is Mott et al., U.S. Pat. No. 6,685,047, entitled Glass Beverage Container with Thermally Insulated Exterior Surface. Mott discloses a mug made of glass whereupon an insulating material such as latex or Neoprene is permanently bonded to the external handle. While Mott reduces thermal transfer, notably of cold, and is limited to glass, the disadvantages of weight and manufacturing complexity are not addressed. Another recent example is Kolowich, U.S. Pat. No. 6,634,417, Thermal Receptacle with Phase Change Material. Kolowich discloses a four-part structure encasing interstitial phase-change material wherein the structure of the side walls taper toward the top opening but are of uniform thickness at any horizontal cross-section, such that hot liquids are rapidly cooled, followed by release of the absorbed heat to maintain warmth. The receptacle disclosed in Kolowich functions to reduce temperature at first, for applications such as baby formula, requires expensive production equipment and special materials. The handle pictured in Kolowich is incidental. Kolowich does not address ergonomics. Another further example is Toida et al., U.S. Pat. No. 6,419,108, “Insulated Beverage Containing Device.” Toida discloses various embodiments of a two-piece, separable container structure with an overlaying sleeve or ring, the interstitial space forming a vacuum, with an inner container of glass, plastic or ceramic, and an outer surface shielded from thermal transfer. No handle is disclosed. Toida reduces weight but requires fabrication, in effect, of two containers that function only in conjunction with their counterpart. Thus none of these recent examples from the prior art address manufacturing simplicity nor ergonomic function.
The manufacture of mugs of the double-wall type of construction requires several production and assembly steps. Additional complexity may be introduced in promotional or commercial settings where the mug is to have affixed trademark or advertising graphics due to the containers' generally circumferential outer wall. The first glance legibility of the decoration or printed material on conventional circular shaped mugs is limited by their inherent curvature field of vision.
The instant invention achieves its insulating and ergonomic properties through a purposefully differential wall thickness achieved by offsetting the foci of the interior fluid-holding chamber of the container from the foci of the entire receptacle. In the preferred embodiment, the foci of the well will be distal to the handle of the receptacle. In the preferred embodiment the resulting elliptical configuration facilitates graphics by the somewhat flattened shape of the receptacle body. Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.